1. Field of the Invention
This invention relates to the manipulation of pictures represented by video signals.
2. Description of the Prior Art
The art of manipulating pictures represented by digital video signals is well established. In essence, the manipulation is accomplished by: digitizing an analog video signal by sampling it and converting each sample, by pulse code modulation, into a binary word or byte representing that sample; storing fields or frames of the digitized signal in memory; and controlling either the reading to or writing from the memory so as to produce from each field or frame a picture that differs from that represented by the input video signal in that at least one geometrical parameter thereof is changed. Such geometrical parameter may, for example, comprise the location of the picture along one or more of up to three axes and/or the angular position of the picture about one or more axes. Other such parameters may comprise the size of the picture (in the horizontal and/or vertical direction thereof), the extent of shearing of the picture, and the perspective of the picture.
FIG. 1 of the accompanying drawing shows in simplified block diagram form the general nature of present day digital video effects (DVE) equipment for effecting such manipulation of a picture. The general kind of apparatus now to be described with reference to FIG. 1 has been embodied in a variety of known proprietary items of DVE equipment, and the operation and construction thereof is well known to those skilled in the art.
The DVE equipment, which is designated 10 in FIG. 1, comprises a unitary piece of hardware containing the components shown in FIG. 1 and described below. A video signal V1 representing a picture P1 that is to be manipulated is inputted into the DVE equipment 10. If, for example, the signal V1 is a color composite signal, it may be supplied to a decoder 12 which produces R, G and B color component signals (for example) on busses 14R, 14G and 14B, respectively. (If the input signal V1 is in analog form, a digitizer (not shown)--for digitizing the signal as described above - may be positioned upstream of the decoder 12).
The R, G and B component signals on the busses 14R, 14G and 14B, respectively, are passed to a picture manipulator which comprises write address generators 16R, 16G and 16B and memories 18R, 18G and 18B for the respective component signals. Each memory 18R, 18G and 18B comprises one or more field or frame stores, and mapping between the locations of words in the fields or frames of the input signals on the busses 14R, 14G and 14B and words of corresponding output signal read from the memories is controlled (in a manner described more fully below) by the write address generators 16R, 16G and 16B in such a manner that the picture P1 is manipulated.
(Alternatively, the signals on the busses 14R, 14G and 14B can be read to the memories 18R, 18G and 18B, respectively, without manipulation, and the manipulation can be effected by read address generators (not shown) used in substitution for the write address generators 16R, 16G and 16B. In either case, the effect is the same.)
The manipulated component signals can then be treated in any one or more of a variety of ways. For example, as shown in FIG. 1, the manipulated signals read from the memories 18R, 18G and 18B can be fed into an encoder which encodesthem to form a color composite video output signal V1(M), representing a manipulated version P1(M) of the input picture P1, which can be broadcast directly or recorded on a video tape recorder. The manipulated color component signals read from the memories 18R, 18G and 18B can also be fed via busses 22R, 22G and 22B to R, G and B inputs of a monitor 24 whereby the manipulated picture P1(M) can be viewed on the screen of the monitor. The signals read from the memories 18R, 18G and 18B may, as shown, be supplied to the busses 22R, 22G and 22B via a mixer 26 which receives other R, G and B inputs from a decoder 28 that receives another color composite video signal V2, representing a picture P2 (which is not manipulated), whereby, as shown on the screen of the monitor 24 in FIG. 1, the manipulated picture P1(M) can be superimposed as a foreground picture on the picture P2 (which thus is a background picture).
The manipulation operation performed by the write address generators 16R, 16G and 16B is effected under the control of a processor 30 which receives command information (representing the picture manipulation desired) from a control panel 32. In a manner known per se, the processor 30 is responsive to the command information entered manually by an operator at the control panel 32 to generate data representing a desired manipulation, such data being applied to the write address generators 16R, 16G and 16B which are responsive thereto to effect the above-described mapping function that causes manipulation of the picture. In more detail, the input picture P1 (prior to manipulation) has a rectangular outline. In general, the manipulation involves moving the locations of at least some of the corners of the picture. The data produced by the processor 30 and applied to the write address generators 16R, 16G and 16B may therefore represent the locations of the corners (and may remain constant from field to field or frame to frame or may vary from field to field or frame to frame, depending upon whether the outline of the picture P1(M) is to remain constant or is to change). In more detail, the processor 30 may provide, for each field or frame, a matrix of data representing the locations of the corners of the manipulated picture P1(M) in the plane of the unmanipulated picture P1, and the write address generators 16R, 16G and 16B may, in a manner known per se, be responsive to such data to effect the above-described mapping operation to achieve the desired manipulation.
As represented by the legend "SYNC" in FIG. 1, vertical and horizontal synchronization information is supplied to the processor 30 to ensure that the data it produces is in synchronization with the video signal V1.
It is known, in the general type of DVE equipment shown at 10 in FIG. 1, for alphanumeric information indicating the current location of the manipulated picture P1(M), as dictated by commands entered via the control panel 32, to be displayed to the operator. Such information may, for example, be displayed on a visual display unit (VDU) 36 connected to the processor 30.
As indicated above, the manipulation performed in the DVE equipment 10 may for example comprise translational and/or rotational movement of the picture P1 with respect to any one or more of three axes. With reference to FIG. 2 of the accompanying drawings, which shows the screen of the monitor 24, the X and Y axes can be those of the plane of the screen, as represented in FIG. 2, and the Z axis may be that passing through the origin of the X and Y axes perpendicular to the plane of FIG. 2. FIG. 2 shows, in similar manner to FIG. 1, a particular form that the manipulated picture P1(M) may adopt, either for an indefinite duration or for one particular field or frame. As will be appreciated, were the picture not manipulated, it would be displayed in a normal manner on the screen, occupying the full area thereof, as represented at P1 in FIG. 2. (That is to say, if no picture P2 were mixed in with the picture P1 and if the picture P1 were not manipulated, the picture P1 would occupy the full area of the screen of the monitor 24.) FIG. 2 indicates generally the mapping operation, as described above, which is performed to effect the manipulation. Thus, in writing to each memory 18R, 18G, 18B, the pixel corresponding to the word occupying the upper left-hand corner of the input picture P1 is so written to the corresponding memory that it occupies an address corresponding to that needed for the upper left-hand corner of the manipulated picture P1(M). A similar operation is performed for every other pixel. It should be noted that the mapping operation may involve very complex hardware. In this regard, the location of each pixel of the manipulated picture P1(M) will generally not correspond exactly to the location of a pixel in the input picture P1 whereby an interpolating filter will be needed to interpolate the positions of the pixels of the output pictures to sub-pixel accuracy. Moreover, the operation of the interpolating pixel may vary from field to field with the extent of manipulation required. Thus, as is known to those skilled in the art, the DVE equipment 10 is a very complex and expensive piece of hardware.
Moreover, although the processor 30 may be largely or wholly software-based, in systems as so far available the software is in substance deeply embedded within the hardware such that it cannot easily be altered.
The manipulations (effect creations) that can be performed using the DVE equipment 10 may be of a variety of forms. One simple form of manipulation or effect creation sequence will now be described, by way of example, with reference to FIG. 3 of the accompanying drawings. The operator first reduces the size of the picture P1 and changes its X and Y coordinates to form a first manipulated picture at a position P1(M1). He does this by entering appropriate commands on the control panel 32, observing the result on the monitor 24. He then enters further commands instructing that the manipulated picture be swept gradually towards the right, to a position P1(M2). He then enters similar commands instructing it to be swept gradually down to a position P1(M3), then to the left to a position P1(M4), and then up back to the position P1(M1), thereby completing a loop. Clearly, and as is well known, many other forms of manipulation involving translation and/or rotation and/or changes in size and/or shearing and/or perspective can be devised. The various commands involved in completing such a sequence may be stored in a data sequence store 34 and saved for future use.
The general form of known DVE equipment described with reference to FIGS. 1 to 3 is subject to several disadvantages. A first disadvantage is that the operator requires a great deal of training in order to use the equipment to devize even simple effects. Such training can be performed only on the actual equipment, which is uneconomical in that it involves taking up the time of a very expensive piece of equipment which could be employed to earn money. A second disadvantage is that even experienced operators may require a very long period of time to devize a particular effect, which again involves uneconomical use of the expensive equipment. These two factors may lead to the need to acquire several pieces of DVE equipment for training and/or devizing effects when only one would suffice for the actual carrying out of effects. A third disadvantage is that since, as explained above, the software that performs the processing carried out by the processor 30 is deeply embedded within the hardware, it is difficult or impossible to add on further desired features after manufacture of the equipment, i.e. either features not thought needed by the user when the system was designed or features devized after the design was effected.
An object of the invention is to reduce the time spent in training operators on expensive equipment that could otherwise be employed more usefully.
Another object of the invention is to reduce the time spent in devizing effects on expensive equipment that could otherwise be employed more usefully.
A further object of the invention is to make it relatively easy to change (e.g. enhance) the processing software.
Yet a further object of the invention is to facilitate the finding of a manipulated picture that has gone off-screen and/or to facilitate the devizing of an effect in which a picture moves between on-screen and off-screen positions.